Recently, with increasing interests in the earth's environment, hydrogen has been drawing considerable attention for its absence of carbon which is a major element of hydrocarbon fossil fuels.
Basically, hydrogen is a gas with no color, smell nor toxic, and has the largest energy generation per mass providing excellent property as a fuel, and numerous research works have been performed around the world to use hydrogen in various ways. In the case of vehicle, two types of research are being made, one being to use hydrogen directly as a fuel for heat engine and the other to use hydrogen for fuel cell.
The merit of hydrogen as a source of energy is that hydrogen generates high energy by reacting with oxygen while producing little pollution.
Therefore, in the modern society which requires low pollution vehicles, hydrogen is attractive as a fuel for heat engines. Also, hydrogen can be used for a wide range of heat engines for air planes, space vehicles and submarines.
The combustion system for hydrogen fueled heat engine, however, has some technical problems that the flame temperature of hydrogen reaches about 3000K at stoichiometric condition presenting the risk of explosion at wide range of concentration in the air of 18-59%. Therefore, there remains a technical challenge to overcome the high flame temperature and unexpected explosion.
To solve these problems, U.S. Pat. No. 7,178,339 discloses a closed-loop cooling system of hydrogen/oxygen combustor for use in submarines, which reduces the temperature of the combustion using water.
This technology, however, requires fresh water which is supplied for reducing the temperature of the combustion chamber, and additional equipment for injecting water to the combustion chamber. The technology does not disclose on the treatment of exhaust gas which is produced in the combustion chamber. Meanwhile, there may be a risk of unexpected explosion due to a high temperature hydrogen leakage resulting from incomplete combustion, which has yet to be addressed in the field.